Field of the Disclosure
The teachings in accordance with the exemplary embodiments of this present disclosure generally relate to an apparatus for controlling speed in railway vehicles, and more particularly to apparatus for controlling speed in railway vehicles in an automatic train operation system.
Discussion of the Related Art
This section provides background information related to the present disclosure which is not necessarily prior art.
In general, an object of automatic train operation (running) is to enable a train to run at a predetermined target speed at each operation section, and to effectively and safely stop at a designated position at a train station, and to efficiently and safely operate the train between stations.
The automatic train operation may be effected without a driver, and even if a driver is available, the driver is not proactively involved in the operation of a train, but provides a minimum part of performing a brake of the train when there is generated an emergency.
In case of a CBTC (Communication-Based Train Control) that is operated by radio communication, protection of train is performed by an ATP (Automatic Train Protection) system, and operations such as control of train speed and the like is performed by an ATO (Automatic Train Operation) system.
The ATP system sets up an ATP speed profile or ATP speed limit in consideration of various factors including a train speed limit at each section, stop position in response to movement authority and safety brake model. The speed limit is transmitted to the ATO system, where the ATO system generates an ATO speed profile in consideration of various factors such as ride comfort and adhesion coefficient, lest the train should exceed the limit.
Then, a controller measures a current speed and sends deceleration/acceleration commands to the train to follow the ATO speed profile generated by the train. Subsequently, the train runs in response to the generated ATO speed profile.
FIG. 1 is a graph illustrating control of a train speed according to prior art.
Referring to FIG. 1, T1 is a current time, Tw is a time when a train exceeds an ATP speed limit for warning, and T2 is a time when the train exceeds an ATP speed limit for emergency braking Although a train runs in response to the ATO speed profile (not shown), if the train exceeds the ATP speed profile or the ATP speed limit, the ATP system activates an emergency brake to eventually stop the train.
To be more specific, albeit being variable according to systems, the ATP speed limit is provided in two types, that is, one is the ATP speed limit for warning and the other is the ATP speed limit for emergency braking, and if the train exceeds the ATP speed limit for warning, the ATP system transmits warning to a driver or a supervisor. However, if the train speed exceeds the ATP speed limit for emergency braking, because no subsequent follow-up action is made in response to the transmitted warning, the train is stopped by the ATP system by activating the emergency braking.
That is, if the train is running at the train speed illustrated in FIG. 1, the ATP system transmits a warning signal to the driver or the supervisor at Tw, and transmits an emergency braking command to the train at T2, whereby the train is stopped by the emergency braking.
As noted from the foregoing, in the conventional automatic train operation system, the ATO generates an ATO speed profile based on the ATP-generated ATP speed limit, and transmits propulsive or braking command to enable a train to trace (follow) the ATO speed profile while not exceeding the ATP speed limit, whereby a train safety is guaranteed.
Thus, in the system like the above, it is general that a safety margin is greatly provided when generating the ATO speed profile to prevent the emergency braking from happening during train operation. Therefore, there is no way but to adopt an operation method based on a conservative viewpoint where a gap between a set value and an allowable limit value is enlarged. That is, there is no way but to allow a train to run at a low speed for fear of an emergency braking being possibly performed, even if the train can run at a faster speed.
Thus, the conventional train operation system suffers from disadvantages in that a train operation frequency at a relevant line is reduced to decrease operational efficiency in the economic viewpoint.